Mechanisms and Functions of Molecular Interactions during Plasmid Rolling Circle Replication

The system under investigation in this project is the replication of plasmid DNA belonging to the pT181 family from the Gram-positive Staphylococcus aureus. This plasmid replicates through an asymmetric rolling circle mechanism, initiated by a plasmid-encoded protein that nicks the supercoiled plasmid allowing unidirectional unwinding by the helicase and elongation by a polymerase. The proteins involved in this process are the replication initiator protein, Staphylococcus aureus RepD, the ATP-driven 3’ to 5’ helicase, Bacillus Stearothermophilus PcrA, and the S. aureus DNA polymerase III. The project is mainly focused on three different aspects of plasmid replication including the formation of the initiation complex, the involvement of DNA polymerase III during plasmid elongation and the analysis of plasmid replication dynamics using AFM imaging. The kinetic mechanism of RepD initiation is examined here. Plasmid nicking occurs at a rate > 25 s-1 (30 °C). Without RepD, PcrA is a poor helicase as it is unable to unwind as short as 20 bp DNA junctions. The function of nicking is also investigated as requirement of PcrA processivity and Rep-PcrA translocation complex. The inclusion of DNA polymerase in these in vitro experiments generates a full in vitro plasmid replication system. The kinetics of PcrA-mediated unwinding has been studied previously, but the involvement of polymerase is little understood. PcrA is able to unwind plasmid DNA at a rate of ~30 bp s-1 (30 °C), however the inclusion of polymerase increased the unwinding rate to ~71 bp s-1 (30 °C). Using a fluorescence-based kinetic approach combined with rapid-mix techniques and AFM imaging, a variety of processes are investigated during RepD, PcrA and PolC mediated DNA replication. These in vitro data would provide an understanding of kinetics and dynamics of several complex processes during plasmid replication

Casos de buenas prácticas en el uso de pequeños generadores con energías renovables

La Matriz Energética Argentina requiere promover su diversificación incentivando la generación eléctrica distribuida, con recursos renovables locales, por parte de pequeños consumidoresproductores inyectando la energía generada a la red de baja tensión. Con este objetivo esta ponencia, elaborada con una mirada integradora que trata de incorporar el uso de las energías renovables al colectivo social y las políticas urbanas locales, se desarrolla conforme a dos aspectos que se consideran significativos: El marco normativo, infiriendo que su existencia y/o sanción debería alentar la generación eléctrica distribuida en bajas potencias, con incorporación al sistema interconectado. El enfoque instrumental a través del análisis de casos - buenas prácticas. Se consideran buenas prácticas a las acciones destinadas a mejorar las condiciones de vida de la comunidad. Conocerlas permite compartir experiencias valiosas incrementando el grado de conciencia de quienes toman decisiones sobre soluciones potenciales a los problemas sociales, económicos y medio ambientales locales.Argentina Energy Matrix requires promoting its diversification by encouraging the distributed electricity generation, with local renewable resources, by small consumers-producers incorporating their generated energy to the distribution networks in low voltage. With this objective this paper, made with an integrative look that seeks to incorporate the use of renewable energies to the collective social and local urban policies, develops according to two aspects that are considered significant: Normative framework, inferring that their existence and/or enactment should encourage the distributed electricity generation in low powers, with incorporation to the grid. Instrumental approach through the analysis of cases - good practice. It is considered good practice to actions designed to improve the living conditions of the community. To know them allows to share valuable experiences increasing the level of awareness of those who take decisions on potential solutions to social problems, economic and environmental premises.Tema 13: Generación distribuida.Facultad de Arquitectura y Urbanism

Casos de buenas prácticas en el uso de pequeños generadores con energías renovables

La Matriz Energética Argentina requiere promover su diversificación incentivando la generación eléctrica distribuida, con recursos renovables locales, por parte de pequeños consumidoresproductores inyectando la energía generada a la red de baja tensión. Con este objetivo esta ponencia, elaborada con una mirada integradora que trata de incorporar el uso de las energías renovables al colectivo social y las políticas urbanas locales, se desarrolla conforme a dos aspectos que se consideran significativos: El marco normativo, infiriendo que su existencia y/o sanción debería alentar la generación eléctrica distribuida en bajas potencias, con incorporación al sistema interconectado. El enfoque instrumental a través del análisis de casos - buenas prácticas. Se consideran buenas prácticas a las acciones destinadas a mejorar las condiciones de vida de la comunidad. Conocerlas permite compartir experiencias valiosas incrementando el grado de conciencia de quienes toman decisiones sobre soluciones potenciales a los problemas sociales, económicos y medio ambientales locales.Argentina Energy Matrix requires promoting its diversification by encouraging the distributed electricity generation, with local renewable resources, by small consumers-producers incorporating their generated energy to the distribution networks in low voltage. With this objective this paper, made with an integrative look that seeks to incorporate the use of renewable energies to the collective social and local urban policies, develops according to two aspects that are considered significant: Normative framework, inferring that their existence and/or enactment should encourage the distributed electricity generation in low powers, with incorporation to the grid. Instrumental approach through the analysis of cases - good practice. It is considered good practice to actions designed to improve the living conditions of the community. To know them allows to share valuable experiences increasing the level of awareness of those who take decisions on potential solutions to social problems, economic and environmental premises.Tema 13: Generación distribuida.Facultad de Arquitectura y Urbanism

Casos de buenas prácticas en el uso de pequeños generadores con energías renovables

La Matriz Energética Argentina requiere promover su diversificación incentivando la generación eléctrica distribuida, con recursos renovables locales, por parte de pequeños consumidoresproductores inyectando la energía generada a la red de baja tensión. Con este objetivo esta ponencia, elaborada con una mirada integradora que trata de incorporar el uso de las energías renovables al colectivo social y las políticas urbanas locales, se desarrolla conforme a dos aspectos que se consideran significativos: El marco normativo, infiriendo que su existencia y/o sanción debería alentar la generación eléctrica distribuida en bajas potencias, con incorporación al sistema interconectado. El enfoque instrumental a través del análisis de casos - buenas prácticas. Se consideran buenas prácticas a las acciones destinadas a mejorar las condiciones de vida de la comunidad. Conocerlas permite compartir experiencias valiosas incrementando el grado de conciencia de quienes toman decisiones sobre soluciones potenciales a los problemas sociales, económicos y medio ambientales locales.Argentina Energy Matrix requires promoting its diversification by encouraging the distributed electricity generation, with local renewable resources, by small consumers-producers incorporating their generated energy to the distribution networks in low voltage. With this objective this paper, made with an integrative look that seeks to incorporate the use of renewable energies to the collective social and local urban policies, develops according to two aspects that are considered significant: Normative framework, inferring that their existence and/or enactment should encourage the distributed electricity generation in low powers, with incorporation to the grid. Instrumental approach through the analysis of cases - good practice. It is considered good practice to actions designed to improve the living conditions of the community. To know them allows to share valuable experiences increasing the level of awareness of those who take decisions on potential solutions to social problems, economic and environmental premises.Tema 13: Generación distribuida.Facultad de Arquitectura y Urbanism

Broadly tunable mid- infrared femtosecond optical parametric oscillator using all-solid-state-pumped periodically poled lithium niobate

We describe a high-repetition-rate femtosecond optical parametric oscillator (OPO) that was broadly tunable in the mid infrared. The all-solid-state-pumped OPO was based on quasi-phase matching in periodically poled lithium niobate. The idler was tunable from approximately 1.7 mm to beyond 5.4 mm, with maximum average power levels greater than 200 mW and more than 20 mW of average power at 5.4 mm. We used interferometric autocorrelation to characterize the mid-infrared idler pulses, which typically had durations of 125 fs. This OPO had a pumping threshold as low as 65 mW of average pump power, a maximum conversion efficiency of .35% into the near-infrared signal, a slope efficiency for the signal of approximately 60%, and a maximum pump depletion of more than 85%. © 1997 Optical Society of America Mid-IR femtosecond pulses have potential applications for the study of dynamics in a variety of materials. Vibrational relaxations in molecules, intersubband transitions in quantum wells, and materials for use in lasers and detectors operating in the 3-5-mm atmospheric transmission window can all be studied effectively with ultrashort mid-IR pulses. In this Letter we report on the generation of mid-IR pulses with an all-solid-state-pumped high-repetition-rate femtosecond (fs) optical parametric oscillator (OPO). The most-common techniques for the generation of high-repetition-rate mid-IR fs pulses are differencefrequency mixing and the use of a synchronously pumped OPO. Difference frequency of the signal and the idler output from Ti:sapphire-pumped OPO's produced fs pulses of between 2.5 and 5.5 mm (Ref. 1) but with maximum average power levels of only 500 mW . Mid-IR synchronously pumped fs OPO's based on KTiOPO 4 and its isomorphs 2 -5 were demonstrated, but they were limited to wavelengths shorter than ϳ4.1 mm. Average power levels greater than 20 mW at 5.2 mm were obtained with KNbO 3 . 6 The all-solid-state-pumped broadly tunable mid-IR fs OPO described in this Letter is based on quasi-phase matching 7 (QPM) in periodically poled lithium niobate (PPLN) and produced more than 20 mW of average power at 5.4 mm. The experimental arrangement was similar to that described in Ref. 8, except that a ring cavity was used instead of a linear cavity. We used a pumping geometry with a small noncollinear angle between the pump and the signal so that the long-wavelength idler beam did not have to be transmitted through any of the cavity optics and optical isolation of the pump laser was unnecessary. The PPLN OPO was synchronously pumped at a repetition rate of 81 MHz by a mode-locked fs Ti:sapphire laser powered by a diodepumped cw frequency-doubled Nd : YVO 4 laser (SpectraPhysics Millennia). The Ti:sapphire laser produced nearly transform-limited pulses of ϳ 90-fs duration, with average power levels of as much as 850 mW over the 790-815-nm wavelength range used in this experiment. We used two optics sets and two PPLN crystals, which were antiref lection coated on both sides with single layers of SiO 2 , in the OPO to cover the tuning range. In both cases the signal was resonated in a ring cavity consisting of two 15-cm radius-of-curvature mirrors, a f lat high ref lector, a f lat output coupler, and a four-prism (SF-14) sequence for dispersion compensation. Several different output couplers were used, with transmission varying from ϳ1% to ϳ9% over the tuning range of the OPO. In a noncollinear fs OPO both temporal walk-off owing to the group-velocity mismatch (GVM) of the interacting pulses and spatial walk-off owing to the noncollinearity of the interacting beams can limit the effective interaction length in the crystal. Near degeneracy 9 the GVM between the pump pulses and signal and idler pulses was of the order of 300 fs͞mm (signal-and-idler-leading pump), 10 resulting in a temporal walk-off length 11 of the order of 330 mm for ϳ100-fs pulse widths. Far from degeneracy, the GVM between pump and signal was reduced to as little as ϳ110 fs͞mm, but the GVM between signal and idler became as large as ϳ260 fs͞mm (signal-leading idler), resulting in a temporal walk-off length of ϳ900 mm between the pump and the signal and ϳ 380 mm between the signal and the idler. For the focusing parameters (ϳ35-mm signal and pump waist radius) and the noncollinear angle (varied from ϳ1.0 ± to ϳ1.6 ± between pump and signal measured internal to the crystal) used in this experiment, near degeneracy the spatial walk-off length of ϳ 550 mm between signal and idler was much larger than the temporal walk-off length and, therefore, did not limit the interaction length. When we were trying to reach long idler wavelengths, however, the increasingly large angle between signal and idler (as large as 9 ± measure

Engineered nonlinear lattices

We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear discrete equation. The proposed structure therefore provides an experimental setting for exploring discrete effects in a controlled manner. In particular, we show propagation of breathers that are eventually trapped by discreteness. When the stripes are wide the beams evolve in a structure we term a quasilattice, which interpolates between a lattice system and a continuous system.Peer ReviewedPostprint (published version

Entangled-Photon Generation from Parametric Down-Conversion in Media with Inhomogeneous Nonlinearity

We develop and experimentally verify a theory of Type-II spontaneous parametric down-conversion (SPDC) in media with inhomogeneous distributions of second-order nonlinearity. As a special case, we explore interference effects from SPDC generated in a cascade of two bulk crystals separated by an air gap. The polarization quantum-interference pattern is found to vary strongly with the spacing between the two crystals. This is found to be a cooperative effect due to two mechanisms: the chromatic dispersion of the medium separating the crystals and spatiotemporal effects which arise from the inclusion of transverse wave vectors. These effects provide two concomitant avenues for controlling the quantum state generated in SPDC. We expect these results to be of interest for the development of quantum technologies and the generation of SPDC in periodically varying nonlinear materials.Comment: submitted to Physical Review

Intrinsic NLRP3 inflammasome activity is critical for normal adaptive immunity via regulation of IFN-γ in CD4+ T cells

The NLRP3 inflammasome controls interleukin-1b maturation in antigen-presenting cells, but a direct role for NLRP3 in human adaptive immune cells has not been described.We found that the NLRP3 inflammasome assembles in human CD4+ Tcells and initiates caspase-1–dependent interleukin-1b secretion, thereby promoting interferon-g production and T helper 1 (TH1) differentiation in an autocrine fashion. NLRP3 assembly requires intracellular C5 activation and stimulation of C5a receptor 1 (C5aR1), which is negatively regulated by surface-expressed C5aR2. Aberrant NLRP3 activity in Tcells affects inflammatory responses in human autoinflammatory disease and in mouse models of inflammation and infection. Our results demonstrate that NLRP3 inflammasome activity is not confined to “innate immune cells” but is an integral component of normal adaptive TH1 responses

Multi-tier Loyalty Programs to Stimulate Customer Engagement

Customers differ in their purchase behavior, profitability, attitude toward the firm, and so on. These differences between customers have led to numerous firms introducing multi-tier loyalty programs. A multi-tier loyalty program explicitly distinguishes between customers by means of hierarchical tiers (e.g. Silver, Gold, Platinum) and assigns customers to different tiers based on their past purchase behavior. Next, customers in different tiers are provided varying levels of tangible rewards and intangible benefits, which are potentially powerful instruments to stimulate customer engagement. In this chapter, we focus on the design and effectiveness of such multi-tier loyalty programs. Building on loyalty program and customer prioritization research, we discuss whether, why, and how multi-tier loyalty programs are effective (or not) in influencing customer behavior, thereby enhancing customer engagement and financial performance